PHA 317 Exam 2 UPDATED ACTUAL
Questions and CORRECT Answers
The flow property of blood can be defined by: - CORRECT ANSWER - viscoelasticity
Which of the following flow patterns exhibited by a drug-dosage form is extremely
unacceptable? - CORRECT ANSWER - Dilatant
Thixotropy is a special characteristic flow that is exhibited by shear thinning systems, such as:
1. Dilatant
2. Plastic
3. Pseudoplastic - CORRECT ANSWER - Only 2 and 3 are correct
(T/F) Concentrated suspensions generally exhibit non-Newtonian flow - CORRECT
ANSWER - True
A plastic material has a yield value of 3000 dynes cm^-2. At shearing stress above the yield
value, F, was found to increase linearly with rate of shear, G. If the rate of shear, G, was 150
sec^-1 when F was 6000 dynes cm^-2, calculate the plastic viscosity? - CORRECT
ANSWER - 20 p
The amount of force per unit area that is applied to a liquid or semi-solid is called: - CORRECT
ANSWER - shearing stress
Under which situation will the viscosity of the oil increase? - CORRECT ANSWER - as
temperature decreases
Which of the following is the most desirable flow characteristic for a dosage form design? -
CORRECT ANSWER - Thixotropic flow
,(T/F) Blood plasma normally slows viscosity only, while whole blood is both viscous and elastic
- CORRECT ANSWER - True
For Newtonian fluids, if the rate of shear is increased two times from its original value while the
viscosity remains constant, what change could you expect in shearing stress of that liquid? -
CORRECT ANSWER - doubled its original value
The Arrhenius equation of rheology expresses the relationship between: - CORRECT
ANSWER - viscosity and temperature
Ostwald viscometer: - CORRECT ANSWER - is used for liquids that flow relatively
easily
(T/F) Pseudoplastic flow has yield value - CORRECT ANSWER - False
(T/F) Thixotropy is a comparatively fast recovery of a material of a consistency lost due to
shearing stress - CORRECT ANSWER - False
A matter that exhibits plastic flow below its yield value would behave as - CORRECT
ANSWER - elastic solid
(T/F) Cup and Bob type of viscometer may be used for gels and pastes - CORRECT
ANSWER - True
Plastic flow is associated with: - CORRECT ANSWER - suspensions
Which one of the following facts is/are correct with respect to thixotropy:
i. Thixotropy is exhibited by shear thinning systems, such as pseudoplastic and plastic liquids.
, ii. Thixotropy can be defined as "an isothermal and comparatively slow recovery, on standing of
a material, of a consistency lost through shearing."
iii. Thixotropy behavior is useful for many pharmaceutical preparations e.g., suspensions
iv. Thixotropic system becomes more viscous upon application of shear. - CORRECT
ANSWER - Only i, ii, and iii are correct
(T/F) The viscoelasticity of an individual's blood changes significantly as the result of
cardiopulmonary bypass surgery - CORRECT ANSWER - True
Which one of the following is the most undesirable flow characteristic for a dosage form design?
- CORRECT ANSWER - Dilatant flow
(T/F) For Newtonian liquids, the shearing stress decreases when the rate of shear increases -
CORRECT ANSWER - False
(T/F) Polymers in solution generally exhibit plastic flow - CORRECT ANSWER - False
1 centipoise is equal to: - CORRECT ANSWER - 0.01 poise
The key factors in the viscoelasticity of blood are:
1. Aggregation
2. Deformability - CORRECT ANSWER - Both 1 and 2 are correct
(T/F) Viscosity is the reciprocal of fluidity - CORRECT ANSWER - True
(T/F) Non-Newtonian fluids have a constant viscosity at a given temperature - CORRECT
ANSWER - False
If the shearing stress is directly proportional to the rate of shear, the liquid exhibits a: -
CORRECT ANSWER - Newtonian flow
Questions and CORRECT Answers
The flow property of blood can be defined by: - CORRECT ANSWER - viscoelasticity
Which of the following flow patterns exhibited by a drug-dosage form is extremely
unacceptable? - CORRECT ANSWER - Dilatant
Thixotropy is a special characteristic flow that is exhibited by shear thinning systems, such as:
1. Dilatant
2. Plastic
3. Pseudoplastic - CORRECT ANSWER - Only 2 and 3 are correct
(T/F) Concentrated suspensions generally exhibit non-Newtonian flow - CORRECT
ANSWER - True
A plastic material has a yield value of 3000 dynes cm^-2. At shearing stress above the yield
value, F, was found to increase linearly with rate of shear, G. If the rate of shear, G, was 150
sec^-1 when F was 6000 dynes cm^-2, calculate the plastic viscosity? - CORRECT
ANSWER - 20 p
The amount of force per unit area that is applied to a liquid or semi-solid is called: - CORRECT
ANSWER - shearing stress
Under which situation will the viscosity of the oil increase? - CORRECT ANSWER - as
temperature decreases
Which of the following is the most desirable flow characteristic for a dosage form design? -
CORRECT ANSWER - Thixotropic flow
,(T/F) Blood plasma normally slows viscosity only, while whole blood is both viscous and elastic
- CORRECT ANSWER - True
For Newtonian fluids, if the rate of shear is increased two times from its original value while the
viscosity remains constant, what change could you expect in shearing stress of that liquid? -
CORRECT ANSWER - doubled its original value
The Arrhenius equation of rheology expresses the relationship between: - CORRECT
ANSWER - viscosity and temperature
Ostwald viscometer: - CORRECT ANSWER - is used for liquids that flow relatively
easily
(T/F) Pseudoplastic flow has yield value - CORRECT ANSWER - False
(T/F) Thixotropy is a comparatively fast recovery of a material of a consistency lost due to
shearing stress - CORRECT ANSWER - False
A matter that exhibits plastic flow below its yield value would behave as - CORRECT
ANSWER - elastic solid
(T/F) Cup and Bob type of viscometer may be used for gels and pastes - CORRECT
ANSWER - True
Plastic flow is associated with: - CORRECT ANSWER - suspensions
Which one of the following facts is/are correct with respect to thixotropy:
i. Thixotropy is exhibited by shear thinning systems, such as pseudoplastic and plastic liquids.
, ii. Thixotropy can be defined as "an isothermal and comparatively slow recovery, on standing of
a material, of a consistency lost through shearing."
iii. Thixotropy behavior is useful for many pharmaceutical preparations e.g., suspensions
iv. Thixotropic system becomes more viscous upon application of shear. - CORRECT
ANSWER - Only i, ii, and iii are correct
(T/F) The viscoelasticity of an individual's blood changes significantly as the result of
cardiopulmonary bypass surgery - CORRECT ANSWER - True
Which one of the following is the most undesirable flow characteristic for a dosage form design?
- CORRECT ANSWER - Dilatant flow
(T/F) For Newtonian liquids, the shearing stress decreases when the rate of shear increases -
CORRECT ANSWER - False
(T/F) Polymers in solution generally exhibit plastic flow - CORRECT ANSWER - False
1 centipoise is equal to: - CORRECT ANSWER - 0.01 poise
The key factors in the viscoelasticity of blood are:
1. Aggregation
2. Deformability - CORRECT ANSWER - Both 1 and 2 are correct
(T/F) Viscosity is the reciprocal of fluidity - CORRECT ANSWER - True
(T/F) Non-Newtonian fluids have a constant viscosity at a given temperature - CORRECT
ANSWER - False
If the shearing stress is directly proportional to the rate of shear, the liquid exhibits a: -
CORRECT ANSWER - Newtonian flow
